Transmission Rank Selection in Shared Radio Cells
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Solution Overview
Problem
Current solutions for transmission rank selection in shared cell deployments are not sufficiently accurate due to decoupling of downlink control channel and data channel transmissions, leading to erroneous channel quality estimations, which are exacerbated by bursty radio traffic with small packet sizes.
Innovation Solution
A method for a base station to select a transmission rank by receiving a channel-state report from a UE, estimating a channel quality parameter reflecting the relation between data channel and control channel receive powers, and using this information to adapt the transmission rank, thereby accounting for differences in transmission points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single physical-layer cell identity is shared among base station and radio units in a shared cell deployment, then device complexity is reduced and resource utilization is improved, but transmission rank selection accuracy deteriorates due to decoupling of control channel and data channel transmissions
Solution Approach 1:
The patent segments the channel quality estimation process into two distinct components: control channel quality estimation and data channel quality estimation. By separately estimating and comparing the quality of control channels (transmitted from base station) and data channels (transmitted from radio units), the system accounts for the decoupling effect in shared cell deployments, thereby maintaining accurate transmission rank selection despite the shared cell identity architecture
Solution Approach 2:
The patent introduces a quality difference parameter that quantifies the disparity between control channel quality and data channel quality. By dynamically adjusting transmission rank selection based on this parameter, the system adapts to the varying channel conditions caused by the decoupling of control and data channel transmissions, resolving the accuracy deterioration issue while maintaining the simplified shared cell structure
2Device complexity
If transmission rank is selected based solely on control channel quality in shared cell deployments, then device complexity is reduced, but transmission reliability deteriorates due to erroneous channel quality estimations
Solution Approach 1:
The patent implements a feedback mechanism where the base station receives quality information for both control channels and data channels, compares these qualities, and uses the quality difference feedback to adjust transmission rank selection. This feedback loop ensures that transmission decisions are based on accurate representations of actual channel conditions, preventing erroneous rank selections that would compromise transmission reliability
3Ease of operation
If traditional rank selection methods are used in shared cell deployments, then ease of operation is maintained, but measurement precision deteriorates due to decoupling of control and data channel transmissions
Solution Approach 1:
The patent introduces an intermediary quality difference parameter that mediates between control channel quality and data channel quality measurements. This intermediary element translates the complex relationship between decoupled channel transmissions into a single adjustable factor that can be applied to traditional rank selection methods, thereby improving measurement accuracy without requiring complete redesign of the rank selection process
Data Source
AI summary
The present disclosure concerns radio communication. In one of its aspects, the technology presented herein concerns a method performed by a base station 210 for selecting a transmission rank. The method may advantageously be carried out when the base station 210 is operating in a shared cell 200. The base station receives a channel-state report from a user equipment. Also, a channel quality parameter is estimated by the base station 210. Furthermore, the base station 210 selects the transmission rank (e.g. transmission rank 1 or transmission rank 2) on the basis of the received channel-state report as well as the estimated channel quality parameter.